Knowing most people, I don't think I would start crying if I was suddenly turned into a baby and also have my memory retained. I would probably yell WHAT THE FUCK.
Speaking isn't something that is physically developed, it's a mental skill; something that you are taught. If you retained all your memory, surely you remember how to talk, and knowing Snips and Snails, I think they would talk if they saw themselves in baby form. So I don't think they still had their own memories.